Infrared floodlighting has significant application to security systems where it is often desirable to illuminate areas with infrared radiation not visible to the unaided human eye. Floodlighting of this type is particularly advantageous when used with closed circuit television surveillance equipment, but can also be used with direct passive viewing devices. Conventional infrared floodlight assemblies of the lens or reflector type typically utilize visible light-absorbing and infrared-transmitting filters located a short distance in front of the floodlight's lens to filter out visible light and pass infrared radiation therethrough. Since appreciable heat is absorbed by such filters, these known floodlight assemblies generally have been relatively large for the wattages involved in order to minimize the power density at the filters. At times, forced cooling has been required. With very few exceptions, cost has limited the filters to the form of flat plates, which in turn has increased the difficulty of producing desired wide beam spreads due to the increased absorption of rays which do not impinge normal to the filter. Consequently, not only is the visible radiation absorbed by such filters but certain infrared bands within the infrared spectrum are absorbed as well.
As mentioned above, the floodlight assembly described in the commonly-assigned. U.S. Pat. No. 4,604,680 employs a floodlight therein which in turn utilizes hot and cold dichroic mirrors as part thereof. Because such a floodlight, or practically any infrared-producing source for that matter, operates at high temperatures and thus generates relatively large quantities of heat, such heat must also be effectively dissipated if the overall structure is to perform satisfactorily.
Accordingly, a need exists for an infrared floodlight assembly capable of providing positive, aligned retention of the floodlight therein in such a manner that effective heat removal from both the lamp and any additional components (e.g., filter) if utilized, can occur, thereby assuring satisfactory operation of the overall assembly. Such a floodlight assembly would clearly represent a significant advancement in the art.